Intraaortic balloon pumping (IABP) has been recognized to have clinical assisting effects in the treatment for heart failure caused by myocardial infraction, or the like, and used worldwide. In IABP, a balloon attached to the tip of a catheter is synchronized with an electrocardiography and associated so as to deflate it at systole of a ventricle and inflate it at diastole of the ventricle, whereby a blood stream in a coronary artery is increased at diastole to reduce ischemia and hence heart failure is improved, and the resistance of the blood stream is reduced at systole and the load of a left ventricle is hence relieved.
A balloon catheter used in IABP is inserted through a femoral artery, and the tip thereof is positioned in the descending aorta of a thoracic part right under the bifurcation of a left subclavian artery. The portion of the balloon catheter out of the body is connected to an IABP apparatus including a pumping system. The inflation and deflation of the balloon is conducted by pumping. Helium or carbon dioxide is used as an operation gas. As normal materials of the balloon part, have been used films formed of various polymeric materials such as polyurethane, polyurethane urea, polyurethane-silicone block copolymers, fluorinated polyurethane, fluorinated polyurethane urea and polymerblends of polyurethane and polydimethylsiloxane.
As described above, IABP has been recognized to have advantageous effects over both diastole and systole and hence is an excellent means as an assisted circulation. However, some side effects have been reported as its clinical application range has extended. As an example thereof, there is an "Intraaortic Balloon Rupture" reported by Kenneth D. Stahl et al., American Society Artificial Internal Organs, Vol. 34 (1988). A particularly grave side effect is to destroy (rupture, damage) the balloon. In the above report, the trouble due to such destruction has been reported to be 2.4% of all cases. The destruction of the balloon part brings not only loss in the effect of assisted circulation on a patient, but also discharging of helium or carbon dioxide as an operation gas into the blood vessel of the patient, resulting in grave side effects such as embolism.
As a protective measure for avoiding such a serious situation, a function to output an alarm signal when the discharging of the operation gas reaches a certain amount or more is incorporated into most of commercially available IABP apparatus. However, it has been known that the operation gas dissolves in the blood least by least due to its diffusion even when the balloon does not leak a gas, and is lost gradually. Therefore, if an alarming mechanism is designed to detect the loss of gas sharply and microscopically, it is difficult to distinguish the loss due to the diffusion from the loss caused by the trouble of the balloon. It is hence impossible to detect the trouble of the balloon in its early stage.
On the other hand, it has been proposed to form balloon parts in sizes and shapes fit for the body build of Japanese and from materials high in thrombus resistance and excellent in mechanical strength with respect to balloon catheters used in IABP (Japanese Patent Application Laid-Open No. 206255/1988). It is desirable to regulate the maximum diameter and length of the balloon parts according to the shapes of the blood vessels of patients and/or the like from the viewpoint of the effect of assisted circulation and the prevention of destruction of the balloon part. However, since the shapes of the blood vessels of the patients greatly vary due to individual difference, the patient's share in expense and doctor's trouble become greater because the sizes of the blood vessels of the individual patients must be measured precisely and the balloon parts must be formed according to such sizes. In addition, the forming operation of the balloon catheters also becomes complicated. Besides, if the volume of the balloon part is made too small with paramount consideration for patient's safety, the effect of assisted circulation owing to IABP is reduced. Further, the conventional materials by which the balloon parts are formed are insufficient in preventive effect against the destruction of the balloon.